1. Field of the Invention
The present invention relates to air conditioning devices, and particularly, to an air conditioning device using solar energy to heat air.
2. Description of Related Art
With increasing CO2 emissions, the risk of global climate becomes abnormal and ecological destruction may increase. As a result, industrialized countries have again become aware of the urgency to reduce their dependence on fossil fuels after the energy crisis in the 70's. Therefore, it has become important to develop new environmental friendly energy resources, and to replace devices using non-renewable energy resources, such as air-conditioners, with devices using renewable energy. The conventional air conditioning devices not only need more energy, but also require refrigerant which can be harmful to the environment. Consequently, these countries have given positive commitments to use solar energy more effectively. Though people still have reservations about whether solar energy will be able to replace other energy resources in the near future, one thing that is almost certain is that solar energy will be playing a very important role in a number of fields, especially air ventilation and heating in structures such as buildings and vehicles.
As far as an air conditioning device using solar energy for heating and air ventilation is concerned, solar collectors are a key part in such a device, and it has to be mounted at an outside location where sufficient sunlight can be collected, such as on a roof or wall. In the past, a lot of effort has been made to develop solar collectors with different functions and styles. Many of them have been disclosed in patent literature. The most typical example is fixing a glass panel or transparent panel onto a fixed outer frame of a heat-insulated chamber and passing fluid through black heat-absorbing plates or pipes installed inside the chamber, so as to absorb solar energy. Examples include the solar hot water supply system disclosed in U.S. Pat. No. 4,418,685, the air ventilation facility disclosed in WO 9,625,632, the roof-style air ventilation facility disclosed in US No. 2002/0,032,000A1, and the wall-style air pre-heater disclosed in U.S. Pat. No. 4,934,338. However, the solar collectors used presently still have some drawbacks. Therefore, there is much room for improvements in applying and promoting the usage of solar energy to save energy and facilitate air conditioning. The aforementioned drawbacks include:
(1) The related solar collector is too heavy. Its long-term use may cause an overly heavy load on the bearing structure.
(2) Solar-thermo conversion efficiency may be limited.
(3) The structure of the related solar collector is complicated, which makes its installation and maintenance difficult. And thus prolongs the return period.
(4) The related solar heating device has poor compatibility and flexibility to match different bearing structures. Very often, it has to be custom-made.
(5) The contour of the solar collector is obtrusive and often impairs the aesthete and harmony of the overall appearance of the bearing structure.
(6) The packaging needed for the collector takes up much space and increases the cost of storage, display, and marketing.
(7) The integral assembly of the whole-unit product is bulky, making it difficult to use in large-area application and increases installation cost.
(8) Glass or transparent panels are glazed onto the outer frame of a heat-insulated chamber. Different thermal expansion coefficients of materials may cause thermal stress problems.
(9) The related design is so complicated as to be difficult for an untrained user to install.
(10) Some of the related designs can only be applicable to the structures which are under construction and designed to allow its installation. For most existing structures, the designs are unsuitable.
(11) When air passes over a glazed panel, heat is dissipated unless double-glazing is used, but it is expensive and troublesome.
(12) Hot water supply systems or liquid systems operated by solar heating experience problems due to freezing and leakage of the working liquid.
Related solar air conditioning apparatuses include that disclosed in U.S. Pat. No. 6,880,553. Heat-absorbing units of the solar air conditioning apparatus of U.S. Pat. No. 6,880,553 are connected in a fixed way, however it is difficult to extend the area of the solar air conditioning apparatus in a convenient way so that the solar air conditioning apparatus can be used in different applications.
It is therefore desirable to provide a solar air conditioning apparatus that can be flexibly extended and used in different applications.